Field of the Invention
The aspects of the present invention relate to a distortion detection method, an exposure apparatus, an exposure method, and a device manufacturing method.
Description of the Related Art
The exposure apparatus is used to manufacture semiconductor devices and flat panel display devices. With high integration of semiconductor devices and definition enhancement of flat panel display devices, refined and multilayered wirings have developed. The process of forming multilayered wiring layers induces a warping phenomenon of a substrate (e.g., wafer or glass substrate) that occurs entirely because film distortions generated during a film-forming operation tend to accumulate in post-processes of a semiconductor manufacturing process. Reshaping the warped substrate into a planer substrate is feasible by causing a substrate chuck provided on a substrate stage of the exposure apparatus to attract and hold the substrate. In this case, local distortions appear in the substrate fixed on substrate chuck. The overlay accuracy decreases.
There is a conventionally proposed method for measuring a plurality of alignment marks formed in each shot region and performing positional alignment in such a way as to improve the overlay accuracy considering such local distortions generated on the substrate.
A scanning type exposure apparatus discussed in Japanese Patent No. 4794882 changes the scanning speed of a stage that scans a substrate according to a warping amount of the substrate so as to correct distortions of respective shot regions.
According to the technique discussed in Japanese Patent No. 4794882, the distortion component corrected with respect to the shot region (i.e., shape) is limited to the magnification in a scanning direction. Therefore, it is desired that exposure apparatuses have the capability of correcting a plurality of types of distortion components in respective shot regions so that the overlay accuracy can be further improved.